Alan Sharp, Richie Burnett, Duncan Cadd and myself recently got together for a mini Teslathon in Burntisland (near Edinburgh)

Alan's church hall

We were amazed when Duncan emptied a pile of bizarre looking wooden, brass, and acrylic parts out of his overnight bag, and proceeded to put together...

Duncan's Wimshurst machine (click for full size)

After some twiddling it was giving sparks up to 7.5cm between spheres. That is something like 75 to 100kV. Not bad! And not a single IGBT in sight!

Alan's OLTC

This was also the maiden voyage of Alan's new OLTC, driven by two Powerex 400A 600V IGBT bricks. It featured several innovations such as an air-cored charging choke and the all-new "Triodal" topload. Although it was limited to less than 600V (we set the crowbar to 500) it produced some very fierce arcs.

The Turbo Triodal Tesla-2

It was also the last appearance of my Tesla-2 spark-gap coil. We tried to measure the DC link voltage and current on it so we would know the power input to compare with the DRSSTC. But on the first run the bearings on the gap motor started to play up. The rotary gap slowed down and began to power arc which shorted the power supply and blew the current meter.

So we decided to give it a proper Viking Funeral. 25nF at 20kV of extra tank capacitors were added, giving the coil three times the bang energy it was designed for. The bearings were soaked with engine oil and everything cranked to full power. The secondary was burnt by racing arcs, the gap electrodes melted, and we blew several 5 amp fuses in the 240v supply. But boy did it look good :-o

We tried several toploads, right up to a 24" x 8", but Alan's triodal seemed to work best. I suspect it compresses space-time to give longer arcs ;) All the expensive parts (power supply, charging choke, caps etc) survived so the Tesla-2 will be rebuilt sometime with a new secondary and better rotary gap.

I also brought the DRSSTC but I never got a good picture of it working. Does anyone else have one?

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